A magnetic random access memory (MRAM) device includes a tunnel junction, or tunnel barrier, that separates a pinned layer that includes a ferromagnet and an antiferromagnet from a sense layer, also known as a free layer, that includes a ferromagnet. In operation, the magnetic orientation of the sense layer in the MRAM device is switched between a magnetic orientation that is parallel and an orientation that is anti-parallel to the magnetic orientation of the pinned layer of the MRAM device. The resistance of the MRAM device varies with the orientation of the magnetization of the sense layer with respect to the pinned layer.
The magnetization of the pinned layer in an MRAM device is set during the manufacture of the MRAM device. The process for setting the magnetization of the pinned layer often includes heating the MRAM device to assist in aligning the magnetization of the pinned layer. During the heating, manganese atoms from a iridium-manganese antiferromagnet in the pinned layer can diffuse and accumulate at the tunnel junction (tunnel barrier) of the MRAM device. This unintended accumulation of manganese atoms at the tunnel junction (tunnel barrier) can degrade or destroy the magnetoresistive properties of the MRAM device.
For these and other reasons there is a need for the present invention.